Operating instructions

Plumbing with auxiliary heat exchanger:
For vehicles with continuous fan operation or high amperage heat exchanger fans, Webasto
recommends the use of an auxiliary heat exchanger with low power consumption and a Webasto
room thermostat (P.N. 560.129).
Heat exchanger kit P.N. 905.670 provides everything necessary for this type of installation.
D: Engine Block Preheating and/or Boost Heating
Fig. 411: Engine Block Preheating and/or Boost Heating
Engine Block Preheating and/or Boost Heating:
1. Remove radiator cap and release system pressure.
2. Drain coolant from engine.
3. Plumb the Webasto system as shown above.
4. Refill engine coolant as per engine manufacturer’s recommendations and re-install the radiator
cap.
410
4 Installation Thermo 90 S